Heritage Action stopped short of urging lawmakers on Saturday morning to reject the conference report for a key water resources and infrastructure bill, but finished the job on Monday by saying it would "key vote" the legislation.

The advocacy group's warning that lawmakers will be graded based on their vote may not be enough to sink the legislation on the House floor under a simple majority vote, but it could jeopardize passage of the bill in its current spot on the suspension calendar, where it will need an affirmative two-thirds majority to pass.

"This massive piece of legislation crosses five out of six red lines," Heritage Action spokesman Dan Holler said in a statement Monday on the Water Resources Reform and Development Act. Holler said the bill's flaws include excessive spending, a failure to privatize a sufficient number of government-funded projects and a lack of provisions to "reduce bureaucracy."

The key vote warning comes just days after the release of the House-Senate conference report for WRRDA, which lawmakers praised as a product of true bipartisanship and a coming-together of members in both chambers.

House GOP leaders lauded the legislation for getting the job done while adhering to Congress's strict earmark ban. They also patted Transportation and Infrastructure Chairman Bill Shuster, R-Pa., on the back for having come up with a process for getting the legislation nearly to the finish line without a mutiny from inside or outside Capitol Hill. The original WRRDA bill came to the House floor last year and passed with only three dissenting votes.

The WRRDA conference report had been considered so noncontroversial that House GOP leaders scheduled its consideration under suspension, an expedited floor procedure typically reserved for bills over which there is little conflict. Now, should enough Republican lawmakers shrink under pressure from Heritage Action, the measure could fail under suspension.

But Republican leaders are not without their options. If the GOP whip team sees danger in WRRDA's defeat under suspension, it could decide to just cut its losses and pull the bill from the Tuesday's schedule, instead popping it onto the Rules Committee docket. The panel would set parameters for a longer floor debate during an already busy legislative week, but it would likely culminate in a simple majority "yes" vote.

Republican leaders could also take the risk of letting the bill fail under suspension and then, after the fact, take it to the Rules Committee for a re-do — a typical maneuver no matter which party is calling the shots in the House.

The key vote announcement is somewhat of a surprise. Holler told CQ Roll Call prior to the conference report's unveiling that Shuster did a good job in keeping stakeholders involved and engaged throughout the process of drafting the legislation, saying that it led to Heritage Action's decision not to key vote the first version of WRRDA last fall.

The choice to score votes now on the conference report means that Holler and his peers weren't satisfied with the version of WRRDA that came out of the bicameral negotiations.